Adjustable stop collar



INVENTOR. Kyi/rg June 13, 1961 w. c. Hl-:MPEL

ADJUSTABLE sToP COLLAR Filed Dec. 5. 1956 YQ. J.

s. "al

United States Patent ADJUSTABLE STOP COLLAR 1 i Y William Clilord Hempel, Manhattan Beach, Calif., assignor to Band W, Inc., Torrance, Calif., a corporation of California Filed Dec. 3, 1956, Ser. No. '626,054

1 Claim. (Cl. 28752)` This invention relates to the art of well drilling and completion and is particularly directed to an improved form of adjustable stop collar which may be mounted on a Well pipe to provide a shoulder. This invention relates to improvements over the device disclosed in the copending application of Kenneth A. Wright and James R. Solum filed December 2, 1955, Serial No. 550,597, now Patent No. 2,872,226.

Dimensional tolerances on commercial grades of well pipe produced by steel mills permit considerable variation in diameter from the nominal size of the pipe. For example, casing having a nominal size of 16 inches outside diameter may vary Within the mill tolerance almost one quarter inch in diameter. This variation makes it dicult to use devices of the type shown in the Wright and Solum application referred to above, because the travel of the wedge slip elements is not great enough to accommodate the Wide variation on diameter of the pipe. Accordingly, it is the principal object of this invention to overcome this disadvantage and to provide an adjustable stop collar which will accommodate wide variations in the outside diameter of the well pipe on which it is mounted. Other and more detailed objects and advantages Will appear hereinafter.

In the drawings:

FIGURE 1 is a side elevation partly in section and partly broken away showing a Well pipe having stop collars mounted thereon and showing a well scratcher mounted loosely on the pipe and located between the stop collars.

FIGURE 2 is a perspective view showing a preferred embodiment of this invention.

FIGURE 3 is a perspective View showing details of construction of one of the Wedge elements.

FIGURE 4 is a sectional View on an enlarged scale showing one of the wedge elements in gripping position.

FIGURE 5 is a side elevation of one of the wedge elements.

FIGURE 6 is a plan view of the Wedge elements shown in FIGURES 3 and 5.

FIGURE 7 is a top plan view of the wedge element in the course of manufacture and prior to iinal shaping operation.

Referring to the drawings, the well pipe or casing 10 may comprise a plurality of sections joined by threaded collars or threaded directly end to end. Well scratchers 11 are loosely mounted upon the casing 10. Stop collar assemblies 12 are mounted on the casing 10 to limit the extent of the axial movement of the scratchers 11. Each of the stop collar assemblies employs an annular collar 13 which may comprise a continuous ring, as shown, or may be formed in two semi-circular halves joined at their ends by hinge connections. Each collar 13 has oppositely directed internal conical surfaces 14 and 15. The collar 13 may advantageously be formed from at stock and welded to form a ring. Window openings 16 are punched out or otherwise formed in the stock before forming in the circle and these window openings 16 are located symmetrically with respect to the internal surfaces 14 and 15.

A plurality of Wedge members 17 are mounted on the collar 13 and each wedge member comprises a pair of oppositely directed wedge elements 18 and 19 connected by an integral oiset web 20. Each wedge element is provided with a serrated front face 21 for engaging the 2,988,385 Patented June 13, 19617 ice \ 2 outer surface of the Well pipe 10. Each wedge element is also provided with a tapered rear face or wedge Asurface/22 for engaging one of the surfaces 14 or 15 on the collar 13. The side edges of the surface 22 may be Y serrated as shown at 23 and 24, while the central portion which is aligned with the web 20 remains relatively Smooth,

Each web 20 extends through one of the window openings 16. Indentations or deformations 25 are formed on the collar 13 in order to reduce the width of the window opening 16 slightly and thereby frictionally retain the wedge members 17 in initial retracted position, as shown in FIGURE 2.

After the wedge members 17 are fully shaped, as shown in FIGURES 3, 4 and 6, they are preferably subjected to a hardening operation such as for example, nitriting, to produce a hard surface or skin on the teeth formed by the serrations 21, 23 and 24. The entire part is nitrited with the result that the outer surface of the web 20 is also hardened.

After the completed members 17 have been installed on the collar 13, the assembly 12 is applied to the well pipe 10 by sliding it axially over one end of a pipe section to the desired location. Hammer blows are then applied to each projecting web 20 and this has the effect of straightening out the dog-leg shape of the web, thereby moving the wedge elements 18 and 19 axially in opposite directions into gripping position as shown in FIGURE 4. Because of the skin hardness of the outer surfaces of the web 20, the web may actually be fractured at 26 by the hammering operation, but this is beneficial since it prevents any action of one of the wedge elements 18 or 19 from applying a tension force to release the gripping action of the other wedge element.

The web 20 is hammered flush with the outer surface of the collar 13. Thereafter the threaded elements 27 are tightened to increase the contact pressure between the wedge elements 18 and 19 and the pipe 10. The threaded elements 27 may comprise internal wrenching set screws and these may be received in the threaded openings 28 provided in the collar 13 adjacent the window opening 16.

The threaded set screws 27 engage the wedge surfaces 22 on the wedge elements 18 and l19 at a location between the serrated edges 23 and 24. The set screws make it possible to tighten the wedge elements 18 and 19 against the pipe 10 when the outer diameter of the pipe is on the low side of the tolerance.

The collar assembly 12 thus serves as a stop to limit axial movement of the well scratchers 11 or of any other device mounted loosely on the well pipe 10 such as for example, casing centralizers (not shown). Axial forces applied to the collar 13 in either direction do not cause it to slip along the surface of the pipe 10, but on the contrary, serve only to wedge the collar more securely in place.

It will be noted that no welding directly on the well pipe 10 is required.

Having fully described my invention, it is to be understood that I do not wish to be limited to the details herein set forth but my invention is of the full scope of the appended claim.

I claim:

In a stop collar assembly for installation upon a well pipe, the combination of: a collar having an annular wall provided with two oppositely tapered surfaces on the interior thereof, the wall having at least one window opening extending therethrough and symmetrically located with respect to said surfaces, the wall having at least two threaded openings adjacent the window open- 4. adapted to engage one of the wedge elements to increase its contact pressure on the pipe.

References Cited in the le of this patent UNITED STATES PATENTS 85,465 McKinney Dec. 29, 1868 465,202 Preston Dec. 15, 1891 1,997,649 Ohlund Apr. 16, 1935 '2,824,613 Baker et al. Feb.,25,'19'58 2,836,447 Wright May 27, 1958 2,872,226 Wright et al. Feb. 3, 1959 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 2968,38@ y t June 13,1961

William Clifford Hempel It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as l`corrected below.

In the grant lines 2 and l2q and in the heading to the printed Specification line 4, for "Band W, Inc., each occurrenceJ read B and W,I Inc.,

Signed and sealed this 13th day of March 1962.

(SEAL) Attest:

ERNEST w. SWIDEEV DAVID L. LADD Attesting Officer Commissioner of Patents 

